Comparison of GHG emissions by sector: Which sectors pollute the most?

Energy sector: The main contributor to GHG emissions

The energy sector remains the primary source of global greenhouse gas emissions, accounting for approximately 73% of total emissions, according to IPCC data. These emissions come primarily from the combustion of fossil fuels to produce electricity, heat, or fuels. Three major sources dominate the energy sector: coal, oil, and natural gas, each with a distinct climate impact.

Fossil Fuels: Emissions Vary Depending on the Source

Coal is the energy source with the highest CO₂ emissions per kilowatt-hour produced, averaging approximately 820 g of CO₂/kWh. Widely used in thermal power plants, particularly in China and India, it still constitutes a significant portion of the global energy mix. Oil, used primarily in transportation and industry, emits approximately 640 g of CO₂/kWh. Finally, natural gas, often presented as a transitional energy, emits approximately 490 g of CO₂/kWh. While its direct emissions are lower, fugitive methane emissions during extraction and transportation must also be taken into account.

Strong regional disparities

The distribution of energy-related emissions varies considerably by region. China is currently the world’s largest emitter in this sector, largely due to its heavy reliance on coal to power its industry and electricity grid. The United States, for its part, has high emissions, but they are gradually declining thanks to the transition to gas and renewable energies. India, experiencing rapid economic growth, is also seeing its energy emissions increase rapidly. Conversely, several European countries, such as France and Sweden, have a more carbon-free energy mix, particularly thanks to nuclear and hydropower.

What are the prospects for the energy sector ?

To break away from this dependence on fossil fuels, low-carbon technologies are being developed, such as the use of renewable energies (solar, wind, hydropower, geothermal). Furthermore, promising innovations, such as small modular reactors (SMRs), currently under development in several countries, aim to produce nuclear electricity more flexibly and securely.

Green hydrogen, produced by electrolysis of water using renewable electricity, also offers a decarbonization avenue for sectors that are difficult to electrify. Several countries, including Germany, South Korea, and Australia, are investing heavily in this promising sector.

Transportation: 16% of global emissions

The transport sector accounts for approximately 16% of global greenhouse gas emissions, according to data from the International Energy Agency. It still relies heavily on the use of fossil fuels, particularly in road transport, which remains the main contributor to these emissions. While mobility is a key driver of economic development, it also poses a major challenge in achieving carbon neutrality targets.

Emissions concentrated in road transport

Approximately 75% of transport emissions come from road transport and reliance on internal combustion engine vehicles. Indeed, passenger cars, trucks, and buses rely heavily on gasoline or diesel, emitting CO₂ directly during combustion.

Air transport is responsible for approximately 11% of the sector’s emissions, and although it represents only a small share of global travel, its climate impact is amplified by emissions at altitude. Maritime transport, often overlooked, contributes approximately 10%, particularly due to the use of highly polluting heavy fuel oil. By comparison, rail transport remains one of the lowest-carbon modes, especially when electrified.

Comparison of emissions by mode of transport

On an individual scale, a long-haul flight can generate several hundred kilos of CO₂ per passenger, while a gasoline-powered car journey emits around 120 g of CO₂/km. Conversely, an electric train can produce emissions below 5 g of CO₂/km/passenger, depending on the electricity source used. This disparity highlights the importance of changing habits and adopting lower-emitting means of transport.

Towards carbon-free mobility: innovations and policies

Faced with the climate emergency, solutions are being developed to reduce transport emissions. Vehicle electrification is growing rapidly, driven by improved batteries, increased range, and purchase incentive policies. Many countries have set deadlines for the end of sales of combustion-engine cars (e.g., 2035 in the European Union).

The development of low-carbon public transport (electric buses, trams, metros) also helps limit emissions in urban areas. Some cities such as Amsterdam, Oslo, and Paris have implemented ambitious policies to promote soft mobility, ban polluting vehicles from city centers, and develop cycle paths.

Other avenues for innovation include alternative fuels: advanced biofuels, green hydrogen, or synthetic fuels produced from captured CO₂. Although still expensive, these fuels could help decarbonize sectors such as aviation and maritime transport.

The role of urban planning and urban mobility

Reducing emissions does not rely solely on technology. Rethinking cities, limiting urban sprawl, and bringing living and working spaces closer together are all levers for reducing the need for travel. Furthermore, individual behavior plays a crucial role: favoring cycling, carpooling, public transport or even limiting air travel are all concrete actions to reduce one’s carbon footprint.

Industry: About 21% of global emissions

The industrial sector accounts for approximately 21% of global greenhouse gas emissions, according to IPCC estimates. This high level is due to the high energy intensity of industrial processes, the massive use of fossil fuels, and direct emissions from chemical reactions. Industry plays a central role in the global economy, but it is also one of the most complex sectors to decarbonize.

High-emitting subsectors

Certain industrial activities account for the majority of emissions:

• Cement production, which alone accounts for approximately 7% of global emissions, generates CO₂ not only through combustion to heat kilns, but also through the chemical reaction to decarbonize limestone.
• The iron and steel industry, essential for steelmaking, still relies heavily on coal-fired blast furnaces, resulting in massive emissions. 
• The chemical industry, particularly the production of ammonia, plastics, and fertilizers, is also highly energy-intensive and produces GHGs, including nitrous oxide (N₂O) and methane (CH₄).

Other sectors such as glassmaking, aluminum, and textiles also contribute to industrial emissions, although to a lesser extent on a global scale.

The central role of energy

Industrial energy consumption still relies heavily on fossil fuels. Coal, natural gas, and oil are used to produce heat and electricity, or to power specific industrial processes. In some countries such as China and India, industry accounts for a dominant share of national energy demand, making its transformation crucial to achieving climate objectives. 

Levers for a Low-Carbon Industry

To reduce its carbon footprint, industry can rely on several levers:

• Improving energy efficiency: modernizing equipment, recovering waste heat, thermally insulating facilities.
• Replacing fossil fuels with low-carbon electricity, hydrogen, or bioenergy.
• Carbon Capture, Storage, and Utilization (CCUS): a technology that captures CO₂ from industrial smokestacks and stores or reuses it. Several pilot projects are underway in Europe, North America, and Asia.
• The Circular Economy: optimizing resource use, recycling materials, and reducing losses upstream of production.

Thus, some industrial groups are taking the lead and innovating to reduce their GHG emissions:

• In Europe, ArcelorMittal is developing a steel production line using hydrogen instead of coal. 
• In France, LafargeHolcim is experimenting with low-carbon cements based on calcined clay or industrial residues.
• Solvay and BASF are investing in green chemistry to reduce the environmental impact of their production.

These initiatives remain costly and limited in volume for now, but they herald the industry of the future: cleaner, more resource-efficient, and integrated into a renewable energy ecosystem.

A sector difficult to transform

The transition of the industrial sector is one of the greatest challenges of global decarbonization. Heavy equipment has long life cycles (often several decades), and the investments required to transform processes are colossal. However, social demand, climate regulations, and rising carbon prices are increasingly encouraging companies to commit to a low-carbon future.

Agriculture: About 14% of global emissions

The agricultural sector is responsible for approximately 14% of global greenhouse gas emissions, but its climate impact extends beyond this figure. Indeed, agriculture closely interacts with land use, deforestation, and food supply chains, making it a complex and cross-cutting sector. Unlike energy or industry, agricultural emissions are not primarily due to CO₂, but to two other, even more potent greenhouse gases: methane (CH₄) and nitrous oxide (N₂O).

Main Sources of Agricultural Emissions

• Methane (CH₄) comes primarily from enteric fermentation in ruminants (cows, sheep, etc.), a digestive process that naturally releases gas. This gas has a global warming potential 25 times greater than that of CO₂ over 100 years. 
• Nitrous oxide (N₂O) is mainly emitted by the use of nitrogen fertilizers and livestock manure. Its impact is even higher: approximately 265 times that of CO₂.

Added to this are emissions linked to intensive plowing, monoculture, energy consumption for agricultural machinery, and food transportation. These practices, often derived from intensive conventional agriculture, also contribute to soil degradation, biodiversity loss, and water resource depletion.

Agricultural practices need rethinking

To reduce these emissions, sustainable alternatives are emerging:

• Conservation agriculture, which limits plowing, covers the soil, and preserves its natural fertility.
• Agroforestry, which combines trees and crops to store carbon and enrich ecosystems.
• Reducing the use of chemical fertilizers, replacing them with organic fertilizers or legumes that naturally fix nitrogen in the soil. 
• Revision of livestock farming practices, through better pasture management, adapted feeding, or a reduction in herd size in certain areas with high animal density.

These different approaches not only reduce emissions but also increase the resilience of agricultural systems to the impacts of climate change.

Food: an indirect but powerful lever

The impact of agriculture on GHG emissions is also linked to dietary choices. In particular, meat production, particularly beef, is much more polluting than that of plant-based proteins. According to the FAO, one kilo of beef emits on average more than 60 kg of CO₂e, compared to less than 5 kg for legumes. Thus, adopting a more plant-based diet, reducing food waste, and favoring short supply chains are all effective levers for reducing the carbon footprint of the agri-food system. 

Agriculture at the Heart of the Ecological Transition

Several countries have already initiated ambitious agricultural transitions:

• In France, the International Strategy for Food Security, Nutrition, and Sustainable Agriculture (2019-2024) encourages the development of agroecology, organic farming, and the reduction of chemical inputs.
• In Brazil, millions of hectares have been restored in the Cerrado, a threatened savannah, thanks to low-carbon agricultural practices supported by international projects.
• In Africa, numerous programs support agroforestry, drought-resilient crops, and soil regeneration techniques.

Agriculture is one of the few sectors that can both reduce emissions and capture carbon, through sequestration in soils and plant biomass. This makes it a key player in achieving carbon neutrality. However, making this transition a success requires profound changes: financial support for farmers, training, access to innovation, adaptation of agricultural policies and reform of the CAP (Common Agricultural Policy) in Europe.

Building and residential: About 6% of global emissions

The building sector, including housing, offices, and public infrastructure, accounts for approximately 6% of global greenhouse gas emissions. These emissions come from both the energy consumption of buildings (heating, air conditioning, lighting, electrical equipment) and emissions incorporated into construction materials (concrete, steel, glass).

Source of emissions: heating, electricity, and materials

Direct emissions from the residential and tertiary sectors are linked to the combustion of fossil fuels (natural gas, fuel oil, coal) for heating and hot water. Added to this are indirect emissions from the production of electricity used in buildings, when this comes from non-renewable sources.

Furthermore, the construction and renovation of buildings also generate a significant carbon footprint. Materials such as concrete (made from cement), steel, and synthetic insulation materials are very energy-intensive to produce. These are referred to as gray emissions, often invisible to users but significant on a building scale. 

Energy Renovation: A Priority Lever

The energy renovation of existing buildings is a crucial lever for reducing emissions in the sector. Indeed, many homes, particularly in Europe, are poorly insulated, poorly ventilated, and heavily dependent on fossil fuels.

Effective solutions exist:

• Efficient thermal insulation (walls, roof, windows).
• Renewable heating (heat pump, wood, solar thermal).
• Double-flow ventilation and LED lighting.
• Home automation and smart sensors to manage consumption.

Countries such as France and Belgium have implemented renovation assistance programs aimed at improving the energy efficiency of the building stock while reducing energy poverty.

New Construction: Aiming for Carbon Neutrality

For new construction, standards are intensifying. In France, the RE2020 (Environmental Renewal) now requires a gradual reduction in carbon emissions from new buildings, also integrating their environmental footprint across their entire life cycle. We’re talking about positive energy buildings (BEPOS) or passive buildings, capable of producing more energy than they consume.

Labels such as BBC (low-energy building), HQE, and BREEAM are also increasingly required in public tenders and private projects.

Innovations are also moving towards:

• The use of bio-sourced materials (wood, hemp, straw, raw earth).
• The reuse of materials from deconstruction.
• Bioclimatic design, which optimizes orientation, thermal inertia, and natural lighting.

Furthermore, some cities are leading the way towards low-carbon neighborhoods:

• In Copenhagen, the Nordhavn district integrates passive buildings, local solar production, and heat sharing between buildings.
• In Freiburg im Breisgau (Germany), the Vauban district combines positive-energy houses, green roofs, and low-energy vehicles. 
• In France, eco-districts such as Dijon Confluence and Issy Cœur de Ville are focusing on functional diversity, energy efficiency, and renewable energy.

What does the future hold for the construction sector?

Long perceived as a slow-moving sector, the construction industry is now undergoing rapid change. Reducing building emissions requires:

• Strong political will to impose ambitious standards.
• Fair financial incentives to support households and businesses.
• Enhanced training for construction tradespeople and professionals.
• A cultural shift, promoting energy efficiency, renovation rather than demolition, and a more streamlined design of spaces.

Other Emitting Sectors: Digital, Waste, and Forests

While major sectors such as energy, transportation, and agriculture account for the majority of global greenhouse gas emissions, other sectors, often considered secondary, also play a significant role in the global carbon footprint. Digital technology, waste, and forest use are three emblematic examples of indirect but growing contributions to emissions.

Digital Technology: An Invisible but Real Footprint

Often perceived as “intangible,” digital technology nevertheless generates very real emissions. Data centers, necessary for data storage and processing, operate 24/7 and require large amounts of energy to cool their servers. According to some estimates, digital technology currently represents between 3 and 4% of global GHG emissions, a figure that is constantly increasing with the explosion in usage.

Video streaming, cloud services, connected objects, and the growth of artificial intelligence are contributing to this increase. For example, one hour of high-definition streaming on a popular platform can generate up to 100g of CO₂, depending on the quality of the connection, the device used, and the location of the servers.

Solutions are emerging: improving the energy efficiency of data centers, powering them with renewable energy, or designing more energy-efficient digital services (eco-design, video compression, local hosting).

Waste: Emissions Often Underestimated

The waste sector is responsible for approximately 3% of global emissions, particularly through the degradation of organic waste in open-air landfills. This fermentation produces methane (CH₄), a greenhouse gas with very high global warming potential.

Emissions depend heavily on the treatment method used:

• Uncontrolled landfills are the highest emitters.
• Incineration releases CO₂ but can be recovered for energy.
• Composting and methanization transform biowaste into resources while reducing emissions.

Reduction at source, efficient sorting, and material recovery (recycling, reuse) are the best strategies for limiting the sector’s carbon impact.

Forests: Carbon Sink or Source of Emissions?

Forests play an ambivalent role in the carbon cycle. On the one hand, they act as natural sinks, absorbing carbon dioxide through photosynthesis. It is estimated that the world’s forests absorb around 2 billion tons of CO₂ each year.

But when they are destroyed, burned, or degraded, they become a massive source of emissions. Deforestation, particularly in the Amazon, Central Africa, and Southeast Asia, contributes both to the release of CO₂ stored in biomass and to reducing future absorption capacity.

Protecting forests, reforestation, restoring degraded areas, and practicing agroforestry are therefore essential actions to preserve this role as a climate regulator. Many carbon offset projects rely on these natural mechanisms.

Regional Comparison of Global GHG Emissions by Sector

Greenhouse gas emissions vary greatly from one country to another, not only in total volume but also in their sectoral distribution. Depending on the level of development, economic model, available natural resources, and public policies, each region of the world displays a unique emissions profile.

Different Priorities by Region

In industrialized countries, emissions are often dominated by:

• Transportation, which can represent up to 30% of national emissions in countries such as the United States, Canada, or France, due to high motorization and ubiquitous road infrastructure.
• The residential and tertiary sectors, particularly in countries with temperate or cold climates where heating accounts for a significant share of energy consumption.
• Indirect emissions, linked to the import of manufactured goods from low-cost countries, which “externalizes” a portion of emissions.

Conversely, in emerging countries such as India, Indonesia, and Brazil:

• Industry (particularly construction, steel, and chemicals) and energy production dominate, due to strong economic growth and demand for infrastructure.
• Agriculture remains a major emissions sector, both for local needs and for exports, as in Brazil and Argentina.
• Deforestation linked to agricultural expansion (soybeans, livestock, palm oil) is also a massive source of emissions.

In less developed countries, particularly in sub-Saharan Africa:

• Total emissions are low, but agriculture often accounts for the majority of emissions, mainly through livestock farming, the use of biomass as an energy source, and deforestation.
• Transportation is still not very motorized, and industry remains weak.
• These countries are nevertheless among the most vulnerable to the impacts of climate change, despite their historically low level of responsibility. 

China, United States, Europe: Three Different Trajectories

China is currently the world’s largest emitter, with a high share of its emissions coming from coal used in power generation and heavy industry. However, it is investing massively in renewables and electrification.

The United States stands out for its very high contribution to road transport. Efforts are focused on electrification, but oil-dependent infrastructure remains a major obstacle.

The European Union displays a more balanced profile, with notable efforts to improve energy efficiency, decarbonize the electricity mix, and regulate industrial emissions. Nevertheless, it remains a net importer of emissions through its trade.

Adapting policies to local realities

This regional diversity means that universal solutions cannot be applied everywhere in the same way. An energy transition plan will not be identical in Germany, South Africa, or India. The challenge is to develop differentiated climate roadmaps, integrating:

• Economic and social specificities,
• Available natural resources (sun, wind, biomass, etc.),
• And the level of technological development.

This differentiated approach is also central to the principle of “common but differentiated responsibilities,” enshrined in the Paris Agreement, which recognizes that all countries must act, but according to their respective capabilities and responsibilities.

What are the 2030/2050 targets for global GHG emissions by sector?

To comply with the Paris Agreement and limit global warming to +1.5°C or +2°C, global greenhouse gas emissions must be halved by 2030 and achieve carbon neutrality around 2050. This requires a profound transformation of all sectors of activity. Each sector must follow a specific trajectory, taking into account its emissions level, its reduction potential, and its technological maturity.

Energy sector: Towards a rapid phase-out of fossil fuels

• 2030 target: Drastically reduce emissions by closing the most polluting coal-fired power plants and increasing the share of renewable energy in the energy mix (target of 60 to 70% depending on the country).
• 2050 target: A nearly completely carbon-free energy system, with massive use of green electricity, clean hydrogen, and smart grids.

Transportation: Rapid Electrification and Changes in Use

• 2030 Target: Achieve at least 30% of global sales of electric vehicles, reduce individual car use, and improve the energy efficiency of transportation.
• 2050 Target: A zero-emission global vehicle fleet, public transportation powered by renewable sources, and a carbon-free aviation and maritime sector thanks to sustainable fuels.

Industry: Decarbonizing Heavy Processes

• 2030 Target: Reduce emissions by 20 to 35%, through improved energy efficiency, coal substitution, and the emergence of the first low-carbon industrial demonstrators.
• 2050 Target: A net-zero emissions industry, relying on technologies such as carbon capture and storage (CCS), the use of green hydrogen in the steel industry, and the large-scale circular economy.

Agriculture and Food: Changing Practices and Diets

• 2030 Goal: Reduce agricultural emissions by 20% through agroecology, reduced use of nitrogen fertilizers, better livestock management, and reduced food waste.
• 2050 Goal: Resilient, low-carbon food systems, combining regenerative agriculture, carbon storage in soils, and a global transition to a more plant-based diet.

Buildings: Energy Efficiency and Low-Carbon Construction

• 2030 Goal: Massive energy renovation of existing buildings (approximately 2 to 3% of the stock per year), and a gradual ban on fossil-fuel boilers in new construction.
• 2050 Goal: A net-zero emissions building stock, where all buildings are efficient, powered by renewable energy, constructed with low-carbon materials, and integrated into sustainable cities.

Other sectors: digital, forests, waste

• Digital: Energy optimization of data centers, development of digital eco-design, reduction of unnecessary energy consumption (objective: stabilize emissions by 2030).
• Forests: Zero net deforestation by 2030, restoration of millions of degraded hectares, recognition of forests as essential carbon sinks by 2050.
• Waste: Drastic reduction of landfills, widespread sorting, recycling, and organic recovery of biowaste.

The Role of Businesses and Citizens in Global GHG Emissions by Sector

Achieving climate targets does not depend solely on governments or major international institutions. Businesses and citizens have a role to play in the transition to a low-carbon economy. Their involvement can accelerate the necessary structural changes in all emitting sectors.

Businesses: From Regulatory Constraint to Strategic Opportunity

Businesses, across all sectors, are both sources of emissions and key players in the transformation. They are increasingly being called upon to measure, reduce, and offset their carbon footprint using several tools:

• The Carbon Footprint or carbon accounting methods (GHG Protocol, ISO 14064) quantify direct and indirect emissions (scopes 1, 2, and 3).
• Initiatives such as the Science Based Targets Initiative (SBTi) help businesses set targets aligned with the Paris Agreement. 
• Non-financial reporting is becoming mandatory in the European Union with the CSRD (Corporate Sustainability Reporting Directive), requiring transparency and measurable actions.

But beyond these obligations, many companies see the ecological transition as an opportunity for innovation, cost reduction, and competitive differentiation. Reducing energy consumption, rethinking the supply chain, eco-designing products, and training employees are all levers that contribute to the sustainable transformation of their business.

Tools like D-Carbonize help structure this approach by facilitating data collection, emissions calculations, and the implementation of targeted action plans by sector.

Citizens: Daily choices with a high impact

On the citizen side, individual actions, although sometimes perceived as symbolic, can have a significant impact when adopted on a large scale. Everyone can take action on the most common sources of emissions:

• Mobility: prioritize walking, cycling, public transportation, or carpooling; Opt for an electric vehicle if necessary.
• Household energy: Improve your home’s insulation, adjust your heating, switch to a green electricity supplier.
• Food: Reduce your consumption of red meat, favor local and seasonal products, and avoid waste.
• Consumption: Limit unnecessary purchases, extend the lifespan of products, buy second-hand, sort and recycle waste.
• Digital: Clear your emails, limit unnecessary HD streaming, turn off your devices, and extend the lifespan of your equipment.

A collective transition

The low-carbon transition can only succeed if businesses and citizens work together, each at their own level. Businesses create the supply, and individuals send strong signals through their demand. Local authorities, for their part, play a mediating role by facilitating infrastructure, support, and regulation. By promoting collaborative approaches and supporting green innovations, it becomes possible to transform each sector of the economy towards a more sober, more resilient model compatible with planetary limits.